1. Field of the Invention
The present invention relates to a device and method for packaging a web roll with a packaging sheet dispenser that dispenses a packaging sheet at an adjustable angle relative to the radial direction of the web roll, that can be moved parallel to the axial direction of the web roll, and on which a supply roll of the packaging sheet is provided, along with a motor-drive for the web roll to be packaged.
2. Discussion of Background Information
A web packaging device is disclosed in GB 1 429 445. As shown in this reference, a web roll, for example a paper roll, is wrapped with a plastic sheet. The plastic sheet has a substantially smaller width than the web roll being packaged. During the packaging process, the plastic sheet is first aligned to the circumferential direction of the web roll and secured thereon. The web roll is then rotated, resulting in the formation of an edge- or end-packaging. After a predetermined number of rotations of the web roll, the packaging sheet dispenser is then turned, such that the width direction of the packaging sheet leaves its orientation parallel to the web roll being packaged and forms an acute angle therewith. When the web roll rotates further, the packaging sheet dispenser simultaneously moves parallel to the axis of the web roll, resulting in helical packaging.
A similar principle is shown in publication DE 195 35 746 A1. Packing paper, whose specific weight is somewhat higher than that of a plastic sheet, is the packaging material used therein.
The advantage to this type of helical packaging lies in the fact that with a single width of packaging sheet, a multitude of web rolls can be wrapped, regardless of their widths. It is not necessary to stock packaging sheets in varying widths. Helical packaging thus simplifies the inventory of packaging sheet material, thereby increasing the economy of roll packaging.
A disadvantage, however, is that it is not sufficient to merely rotate the web roll a number of times corresponding to the amount of packaging sheet layers desired, for example two or three times. A multitude of rotations are necessary before the web roll is enveloped along its entire length. This requires increased packaging time. Moreover, the possibility for increasing packaging speed is limited. Especially when using packing paper, there is considerable danger of the packaging sheet tearing if wrapping velocity is increased too much within a short period of time. Increased wrapping velocity, however, is necessary for attaining higher packaging speeds.